1. Field of the Invention
The present invention relates to a computer-aided diagnosis system for medical use, which outputs computer-aided diagnosis data for medical images using a computer.
2. Description of the Related Art
Recently, a computer-aided diagnosis system (hereinafter referred to as a CAD system) for medical use has been developed in which the features of medical image data are determined and computer-aided diagnosis data (hereinafter referred to as CAD data) for assisting a doctor are obtained by using a computer. It is, however, cumbersome for a doctor to operate a computer to obtain the CAD data during the diagnosis, resulting in an adverse effect on a reading operation of image in terms of both time and labor. Further, the conventional CAD system itself cannot provide a high precision CAD data required for the diagnosis.
Examples of such CAD systems are disclosed in U.S. Pat. No. 4,851,984 and U.S. Pat. No. 4,839,807. The CAD systems described in the above USPs comprise means for inputting a medical image, means for analyzing the medical image using a predetermined CAD algorithm, and means for displaying an analysis result.
The doctor refers to the output of the CAD system at the time of reading of the medical image to prevent an oversight of a shadow image of the abnormal portion.
To obtain the CAD data, the following proceedings are required. Locations of one type of abnormal shadow images, e.g., an abnormal shadow image of the interstitial lung disease, are detected on a conventional X-ray radiograph and the result of the detection is output. Therefore, the medical image on the X-ray film is digitized. A rib, an object of the analysis, is identified in the medical image. A region of interest (hereinafter referred to as a ROI) is set on the medical image, as described in the U.S. Pat. No. 4,851,984. The data in the ROI is frequency-analyzed to extract the amount of physical texture of the image. The shadow image is classified into groups based on the amount of physical texture. A display device displays the digital image and the type, degree, and position of the shadow image in an overlapping manner.
The reading operation by the doctor is to draft the reading report. Before drafting the report, the doctor refers to the CAD data to prevent an oversight of a shadow image.
If the doctor needs the CAD data, the above proceedings must be performed. That is, the medical image must be digitized before the CAD system starts to operate. The digitized image is analyzed by the computer using the above proceedings and the analysis result is output to an attached display device. The doctor continues the reading of the image after watching the CAD result.
The above described CAD system has the following drawbacks.
The same CAD algorithm which is included in the CAD system is applied to the image data regardless of the type of the image. For example, the same CAD algorithm is applied to a conventional X-ray radiograph of chest as well as a CT image. Therefore, an unexpected CAD result is obtained thus lowering the ability of diagnosis.
The CAD system includes only one CAD algorithm for a given disease. Therefore, it is not possible to obtain a plurality of CAD data for a plurality of diseases. Therefore, if ten diseases are to be detected from one image based on the CAD data, the image data must be input to ten CAD systems and ten CAD data must be output. This increases the time and labor for the CAD operation.
A time for merely reading the image without outputting the CAD data is about three minutes. A time from requesting a kind of CAD operation to output the CAD data is about two minutes. If the CAD operation is performed during the reading, it takes a long time for reading and a difficulty occurs for the reading.
The CAD data includes many items, e.g., the position, type, and degree of the abnormality. In the conventional CAD system, all the items of data are output, thereby the output becomes complicated.
The CAD system does not store the CAD result, therefore, if the CAD operation is requested for the image which has been once analyzed, the same CAD operation is repeated thus wasting the time.
Meanwhile, a picture archiving communication system (hereinafter referred to as a PACS) for transferring, storing, and displaying the medical images has been developed. In the PACS, digital medical image data archived by modalities including a digitizer and attribute data thereof are transferred via a network and are stored in a large capacity recording means such as an optical disk device. Desired data are retrieved by using a data base system. The image data is transferred to a workstation via the network and is displayed However, the prior PACS does not function a CAD operation.